What class of amplifier has the most high definition sound ?

To win, you:
 
1. can't have an amp with crossover distortion (sorry class AB)
2. can't have an amp that isn't linear & has an output filter (sorry class D)
3. can't cheat and use a bunch of feedback to lower distortion. (sorry class AB & D).

What we are left with is Class A solid state for accuracy (pure sound?) and tubes for adding those lovely harmonics that give us that deep and wide sound stage, extra decay, and rounded notes. 

I would say it somewhat differently - tubes presenting harmonically correct soundscapes.

I would say it somewhat differently - tubes presenting harmonically correct soundscapes.

Only Class-A OTL's, anything with an output transformer is hamstrung.

Cheers George 

what class of amp is the High Definition kind?

short answer? The High Dollar kind.

almost invariably greater fidelity goes hand in hand with more investment. despite ‘class’.

A, A/b, D, Hybrid, Tube amps which have an enormity of classes based on their output tubes, all have different levels of audio definition, or resolution. as the entry fees escalate in each camp, usually their resolution increases commensurately. there are over achievers and we all seek them out, but usually, more money means better most often. 

 the buyer beware note here is that it will take more than just an amp to realize the amps true abilities.

there needs be a great source, and of course, great speakers, or at least very competent ones.

a pair of Hiesenberg monos at $100K running into a pair of say, Joeseph Audio Pulsars isn’t gonna express the entire bandwidth as revelatory as they would with say, a pair of Legacy Aries.

amps are key, but so is the rest of the rig.